The provision of adequate supplies of fresh water is a continuing and mounting problem worldwide. In many countries, the process of desalination of saline water, such as sea water, brackish water or saline industrial waste water, is used to supply fresh water. In Australia alone, it is predicted that approximately 460 gigaliters per annum of drinking water will be produced from desalination plants by 2013.
Typically, reverse osmosis (RO) membranes are used in desalination plants to desalinate sea water, brackish ground water and/or saline industrial waste water. The main objective of the desalination process is to reduce the salt (sodium chloride, NaCl) concentration of saline water to less than 0.5 grams per liter (g/L) suitable for drinking water. The salt concentration of sea water is typically 35-45 g/L.
Unfortunately, the use of desalination processes to produce fresh water from saline water present a number of environmental issues. For example, one of the by-products of the desalination process is brine waste which typically has a salt concentration of about 70 g/L. The highly saline liquid brine waste stream has to be disposed of and the typical methods used to do that include discharging it back to the ocean, disposing of it in the sewer, injecting it into deep wells, applying it to land, or transferring it to evaporation ponds. In each case, disposal of the waste imposes significant economic and/or environmental costs.
Ideally, brine waste from desalination processes would be used to form other, value added materials.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.